As a developing device, there is known a developing cartridge that is detachably mounted on an image forming apparatus and is configured to develop an electrostatic latent image on a photosensitive drum (for example, refer to JP-A-2009-168993)
The developing cartridge described in JP-A-2009-168993 includes a housing which accommodates toner and rotatably supports a developing roller configured to carry the accommodated toner. In forming an image, the developing roller contacts a photosensitive drum over as entire area thereof in a rotational axial direction of the developing roller and is rotated to supply toner to an electrostatic latent image formed on the photosensitive drum. Accordingly, it is possible to develop the electrostatic latent image on the photosensitive drum.
Herein, the developing cartridge is provided with a blade assembly. The blade assembly has a layer thickness regulating blade which is configured to contact a circumferential surface of the developing roller and regulate a thickness (layer thickness) of the toner on the circumferential surface of the developing roller, and a blade holder which supports the layer thickness regulating blade.
In the developing cartridge described in JP-A-2009-168993, as viewed from the rotational axial direction of the developing roller, the blade holder is bent. In the blade holder, the layer thickness regulating blade is attached to one side with respect to the bent part and the other side with respect to the bent part is attached to the housing. In other words, in the blade assembly, as viewed from the rotational axial direction of the developing roller, the layer thickness regulating blade and the part attached to the housing (the other side of the bent part) are not provided on a same plane.
Therefore, if a difference exists in a bending angle of the blade holder, an error may occur in the positioning of the layer thickness regulating blade with respect to the circumferential surface of the developing roller. If such error occurs, it is difficult for the layer thickness regulating blade to uniformly regulate the layer thickness of the toner on the circumferential surface of the developing roller over the entire area of the developing roller in the rotational axial direction.